The present disclosure relates generally to the field of fabrication of semiconductor devices, and more specifically to a method of fabricating a 3D CMOS device such as a fin-type field effect transistor (finFET), or a portion thereof.
Multiple-gate metal-oxide semiconductor field-effect transistors (MOSFETs) are MOSFETs that incorporate two or more gates into a single device. Some of these devices may be known as finFETs when their structure includes a thin “fin” extending from a substrate. Planar versions of the double-gate MOSFETs also exist without the fin. Silicon based finFETs have been successfully fabricated using conventional MOSFET technology. A typical finFET is fabricated on a substrate with an overlying insulating layer with a thin ‘fin’ extending from the substrate, for example, etched into a silicon layer of the substrate. The channel of the FET is formed in this vertical fin. A gate is provided over (e.g., wrapping) the fin. The multiple gate structure is beneficial in that there is a gate on both sides of the channel allowing gate control of the channel from both sides. Further advantages of finFETs include reducing the short channel effect and higher current flow.
However, introducing the suitable dopants into the fins of a finFET device may be difficult. For example, challenges arise in ensuring conformal sidewall doping. Current processes can lead to random doping fluctuations, poor step coverage, and/or other issues. Additionally, in particular as aspect ratio (e.g., fin height versus fin width) increases, implementing a method of doping the fin of a transistor, which can be integrated with a process or doping the fin adjacent transistor of a different type may be difficult.